KR101194846B1 - Apparatus and method for manufacturing silicon thin plate using continuous casting - Google Patents

Abstract

Disclosed are a silicon thin film manufacturing apparatus and method using a continuous casting method that can contribute to the improvement in productivity and quality of silicon thin film manufacturing.
Silicon thin film manufacturing apparatus using a continuous casting method according to the present invention comprises a silicon raw material input unit is supplied with a silicon raw material; A silicon melter for melting the supplied silicon raw material to form a silicon melt; A silicon molten metal storage unit configured to receive and store the molten silicon, and then discharge the molten silicon into a melt having a predetermined thickness; A lower transfer substrate disposed under the silicon molten metal storage unit and transferring the discharged silicon melt; And a silicon sheet forming part for cooling the transferred silicon melt to form a thin plate. The silicon melt storage part may have a surface temperature of 1300 ° C. to 1400 ° C. and a temperature of the lower transfer substrate. It is 1400 ℃, the movement speed of the lower transfer substrate is characterized in that 300 ~ 1400 cm / min.

Description

Apparatus and method for manufacturing silicon thin plate using continuous casting method {APPARATUS AND METHOD FOR MANUFACTURING SILICON THIN PLATE USING CONTINUOUS CASTING}

The present invention relates to a manufacturing technology of a silicon thin plate that can be used as a solar cell substrate, and more particularly, a silicon thin plate manufacturing apparatus using a continuous casting method that can contribute to high productivity and quality improvement by using a continuous casting method (continuous casting) And to a method.

Silicon substrates, a key component of silicon solar cells, account for about 28% of solar cell module prices.

Generally, a silicon substrate for a solar cell is manufactured by melting a silicon, solidifying the molten silicon to produce a single crystal silicon ingot or a polycrystalline silicon block, and then cutting through several cutting processes.

In the case of the silicon substrate manufacturing method, the silicon raw material loss is generated 40-50% by the cutting process, which is the main cause of the increase in manufacturing cost.

In order to fundamentally eliminate such cutting loss, a technique for producing a silicon substrate directly from the molten metal has been developed.

The direct manufacturing technology of silicon substrates is divided into a vertical growth method and a horizontal growth method. The vertical growth method is already in mass production, but the growth rate is slow. On the other hand, the horizontal growth method has not been mass-produced despite the high growth rate.

In the case of the conventional horizontal growth method for direct silicon production, there is typically a ribbon growth on substrate (RGS) method. However, the RGS method controls the solidification inside the molten silicon storage container and has the following problems because the shape is controlled by using a blade.

First, in the case of the RGS method, the solidification is controlled inside the molten silicon storage container. In order to cause the solidification inside the container, the solidification time must be controlled to less than a millisecond (msec). If only a small amount of solidification time is passed, the solidified substrate may be caught in the blade, and the device itself may be damaged.

In addition, in order to uniformly solidify, the temperature of the silicon melt must be uniformly controlled over the entire substrate area. However, it is very difficult to uniformly control the temperature of the molten silicon melt.

In the case of the RGS method, a blade is used to control the shape of the substrate. In this case, there is a high probability that the blade is broken, and mechanical contact between the blade and the silicon substrate has a high possibility of causing contamination of the substrate.

Therefore, the conventional silicon substrate direct manufacturing technology has a trade-off between the productivity of the silicon substrate and the energy conversion efficiency. Therefore, the silicon substrate manufacturing technology, which can be applied to solar cell substrates and the like, increases both the productivity and quality of the silicon substrate. Required.

SUMMARY OF THE INVENTION An object of the present invention is to use a continuous casting method that facilitates continuous production and physical property control, and to produce a silicon thin film directly from the molten silicon, and to improve the surface quality of the silicon thin film produced. It is to provide a silicon thin film manufacturing apparatus used.

It is another object of the present invention to provide a method for producing a silicon thin film which can eliminate silicon cutting loss by manufacturing a silicon thin film directly from the molten silicon using a continuous casting method.

Still another object of the present invention is to provide a solar cell substrate manufactured by using a continuous casting method and having excellent surface quality.

Silicon thin plate manufacturing apparatus using a continuous casting method according to the present invention for achieving the above object is a silicon raw material input unit is supplied with a silicon raw material; A silicon melter for melting the supplied silicon raw material to form a silicon melt; A silicon molten metal storage unit configured to receive and store the molten silicon, and then discharge the molten silicon into a melt having a predetermined thickness; A lower transfer substrate disposed under the silicon molten metal storage unit and transferring the discharged silicon melt; And a silicon sheet forming part for cooling the transferred silicon melt to form a thin plate. The silicon melt storage part may have a surface temperature of 1300 ° C. to 1400 ° C. and a temperature of the lower transfer substrate. It is 1400 ℃, the movement speed of the lower transfer substrate is characterized in that 300 ~ 1400 cm / min.

Silicon thin plate manufacturing method using the continuous casting method according to the present invention for achieving the above another object comprises the steps of (a) preheating the lower transfer substrate to form a discharge portion on the lower side of the molten silicon storage (S410); (b) charging the silicon raw material into the silicon melt (S420); (c) melting the silicon raw material charged in the silicon melting unit to form a silicon melt (S430); (d) opening the gate under the silicon melter to tap the silicon melt (S440); (e) storing the melted silicon melt in the silicon melt storage unit (S450); (f) driving the lower transfer substrate to discharge the silicon melt (S460); And (g) cooling the silicon melt carried by the lower transfer substrate to form a thin plate (S470).

Silicon thin film for a solar cell according to the present invention for achieving the above another object is manufactured by the method presented above, characterized in that having a thickness of 200 ~ 400㎛.

Silicon thin film manufacturing apparatus and method using the continuous casting method according to the present invention can essentially remove the silicon cutting loss by using a continuous casting method that is easy to control productivity and properties. Therefore, productivity of silicon thin plate manufacture can be improved.

In addition, the apparatus and method for manufacturing a silicon thin plate using the continuous casting method according to the present invention can improve the quality of the silicon thin sheet manufactured by optimizing process parameters and applying an inert gas blowing.

Therefore, the silicon thin plate manufactured using the apparatus and method for manufacturing a silicon thin plate using the continuous casting method according to the present invention can be applied to a substrate for a solar cell.

1 schematically shows an apparatus for manufacturing a thin silicon sheet using a continuous casting method according to an embodiment of the present invention.
Figure 2 shows an example of a graphite crucible that can be applied to the present invention.
Figure 3 shows another example of a graphite crucible that can be applied to the present invention.
4 is a flowchart illustrating a method of manufacturing a silicon thin plate using a continuous casting method according to an embodiment of the present invention.
FIG. 5 is a photograph showing a surface of a silicon thin film manufactured by the method illustrated in FIG. 4.
FIG. 6 is a photograph showing a bottom surface of a silicon thin plate manufactured by the method illustrated in FIG. 4.
FIG. 7 is a photograph showing a surface after polishing the surface of the silicon thin plate shown in FIG. 5.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the examples described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the examples disclosed below, but may be implemented in various forms, and only the examples are intended to complete the disclosure of the present invention and those skilled in the art to which the present invention pertains. It is provided to fully inform the scope of the invention, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, an apparatus and method for manufacturing a silicon thin plate using the continuous casting method according to the present invention will be described in detail with reference to the accompanying drawings.

1 schematically shows an apparatus for manufacturing a thin silicon sheet using a continuous casting method according to an embodiment of the present invention.

Referring to FIG. 1, the illustrated silicon thin film manufacturing apparatus 100 includes a silicon raw material input part 110, a silicon melt part 120, a silicon melt storage part 130, a lower transfer substrate 140, and a silicon thin film forming part. And 150.

The silicon raw material input unit 110 supplies the silicon raw material from the outside and inputs the silicon raw material in a predetermined amount into the silicon melting unit 120.

The silicon melter 120 melts the supplied silicon raw material to form a silicon melt.

In the case of silicon, unlike the metal, at a temperature of about 700 ° C. or less, the electrical conductivity is low, so that direct heating by electromagnetic induction is difficult. Therefore, the silicon raw material can be melted in an indirect melting method by crucible heat. In the case of silicon melting by the indirect melting method, the crucible may be a graphite crucible. In the case of graphite, the crucible may be easily heated due to electromagnetic induction because the electrical conductivity and the thermal conductivity are very high.

However, when silicon is indirectly melted by graphite crucible heat, there is a problem of contamination of silicon or the inner surface of the crucible.

Therefore, it is desirable to minimize the contamination problem of silicon by indirectly heating the silicon by crucible heat at a temperature of 700 ° C. or lower, and non-contact melting of the silicon raw material through induction melting at a temperature above that.

When the silicon raw material is melted by the induction melting method, the silicon melting part 120 includes a crucible 121, an induction coil 122, a tapping part 123, and a gate 124, as shown in FIG. 1. It may be an induction melting apparatus.

The crucible 121 stores a silicon raw material, and a tapping part 123 is formed at a lower portion thereof. Induction coil 122 surrounds the outer wall of the crucible 121. Induction coil 122 is connected to an AC power source. The gate 124 opens and closes the tapping part 123 formed under the crucible 121. The gate 124 may be bar type or valve type as shown in FIG. 1.

In order to apply the silicon induction melting method, a water-cooled crucible may be applied first. However, in the case of a water-cooled crucible, there may be a problem that low heat dissipation efficiency of silicon exists.

Therefore, in the present invention, it is preferable that the crucible 121 is capable of increasing the melting efficiency while allowing induction melting of silicon instead of the water-cooled crucible.

For example, a graphite crucible in which slits are formed in the longitudinal direction as shown in FIGS. 2 and 3 may be provided.

Figure 2 shows an example of a graphite crucible that can be applied to the present invention.

Referring to FIG. 2, the illustrated graphite crucible has a cylindrical structure in which a plurality of longitudinal slits 230 penetrating the outer wall 210 and the inner wall 220 are formed.

In the case of the graphite crucible shown in FIG. 2, unlike the general graphite crucible, a plurality of slits 230 are formed in the longitudinal direction. In the case of the general graphite crucible, electromagnetic waves are shielded by the graphite even if an AC power is applied to the induction coil 122, and the electromagnetic force hardly acts inside the crucible.

However, when the longitudinal slits 230 are formed, the electromagnetic wave is not shielded despite being a crucible made of graphite, and it was confirmed that the electromagnetic force acts strongly toward the center of the crucible. As a result, silicon was induced and melted without forming contact with the inner wall of the crucible by electromagnetic force acting toward the center of the crucible to form a molten silicon.

The plurality of longitudinal slits 230 may be formed from the top of the crucible to a portion of the bottom surface 240 of the inside of the crucible. In addition, the plurality of slits 230 are symmetrically formed along the circumference of the crucible.

Figure 3 shows another example of a graphite crucible that can be applied to the present invention.

The crucible shown in FIG. 3 is a graphite crucible. The crucible shown in FIG. 2, in addition to the crucible outer wall 210 and the plurality of longitudinal slits 230 penetrating the inner wall, extends from the edge of the crucible bottom 240 to the center direction. A plurality of slits 310 in the direction are further formed.

For convenience, the plurality of longitudinal slits 230 passing through the crucible outer wall 210 and the inner wall are called first slits, and the plurality of slits 310 in the longitudinal direction are centered from the edge of the crucible bottom surface 240. This is called the second slit.

The second slit evenly distributes the eddy current concentrated in the downward direction from the first slit to the inner bottom surface 240 so that the electromagnetic force is directed upward. Through the second slit, contactless contact with the bottom surface as well as the inner wall of the crucible during induction melting of silicon can minimize contamination of silicon.

Next, the silicon molten metal storage unit 130 receives and stores the molten silicon, and then discharges the molten silicon into a melt having a predetermined thickness.

As shown in FIG. 1, the lower surface of the silicon melt storage unit 130 may be open, and in this case, the lower transfer substrate 140 disposed under the silicon melt storage unit 130 may include a silicon melt storage unit ( 130 will be defined.

In addition, the molten silicon storage unit 130 has a discharge portion 132 is formed to discharge the molten silicon on the lower side. The discharge part 132 may be a separate discharge groove, and as shown in FIG. 1, a lower surface of the discharge part 132 may be defined by the lower transfer substrate 140.

The thickness of the discharge part 132 may be one element that determines the thickness of the silicon thin plate, and may be about 0.2 to 2 mm.

In addition, a cooling device (not shown) may be disposed adjacent to the discharge part 132, and in this case, the silicon melt may be discharged from the silicon melt storage part 130 in a cooled state or a supercooled state.

The lower transfer substrate 140 is disposed under the silicon melt storage unit 130, and continuously transfers the silicon melt discharged from the silicon melt storage unit 130.

The lower transfer substrate 140 is preferably preheated by the preheater 142 in order to minimize the temperature difference with the molten silicon.

The lower transfer substrate 140 is preferably formed of a material having a different coefficient of thermal expansion from silicon. When the thermal expansion coefficient of the lower transfer substrate 140 is different from the silicon, the silicon thin plate manufactured after the cooling of the silicon melt may be easily separated from the lower transfer substrate 140, and the lower transfer substrate 140 may be reused.

The lower transfer substrate 140 may be a metal or ceramic, and specifically, the lower transfer substrate may be SiC, Si ₃ N ₄ , graphite, graphite, high density carbon, Al ₂ O ₃ , molybdenum (Mo), etc. It may be used as a material of the substrate 140, and more preferably SiC, Si ₃ N ₄ may be presented as the material of the lower transfer substrate 140.

The lower transfer substrate 140 may be formed of a single substrate, and may be separated into a lower substrate which is in contact with the transfer substrate responsible for the transfer and the silicon melt and forms the silicon thin plate.

The silicon thin plate forming unit 150 cools the silicon melt to be transferred to form a thin plate.

In the present invention, the silicon thin plate forming unit 150 may cool the silicon melt by an inert gas blowing method such as argon gas, helium gas, nitrogen gas, or the like.

In the case of inert gas blowing, it is possible to contribute to the rapid cooling of the silicon melt to remove the remaining melt, and it is also easy to control the surface shape of the silicon thin film produced through the surface planarization.

The amount of inert gas blown may be 0.1 ~ 2 Nm ³ / h, but is not necessarily limited thereto. The amount of inert gas blown may vary depending on the position and shape of the silicon thin film forming portion 150.

When using the silicon thin film manufacturing apparatus shown in FIG. 1, the productivity and quality of the silicon thin film to be produced are greatly influenced by the surface temperature of the silicon melt inside the molten metal reservoir, the temperature of the lower transfer substrate, and the transfer speed of the lower transfer substrate. Can be. These process variables each affect the productivity of the silicon sheet produced through a complex action rather than affecting each one alone.

Preferably, the surface temperature of the silicon melt in the silicon molten metal storage unit 130 is 1300 ~ 1400 ℃, the temperature of the lower transfer substrate 140 is 800 ~ 1400 ℃, the moving speed of the lower transfer substrate 140 is 300 ~ 1400 cm / min.

If the surface temperature of the silicon melt in the silicon melt storage unit 130 is less than 1300 ° C., the silicon melt may harden before discharge. If the surface temperature of the silicon melt exceeds 1400 ° C., the silicon melt flows during the transfer process after discharge. There is a problem that can be lowered.

In addition, when the temperature of the lower transfer substrate 140 is less than 800 ° C., the molten silicon may harden at a portion where the lower transfer substrate 140 is in contact with the silicon melt, and the temperature of the lower transfer substrate 140 exceeds 1400 ° C. If there is a problem that the silicon melt can flow.

In addition, when the feed rate of the lower transfer substrate 140 is less than 300cm / min, the thickness of the silicon thin plate to be manufactured may be excessively thick, on the contrary, if the feed rate of the lower transfer substrate 140 exceeds 1400cm / min There is a problem that the silicon thin film becomes too thin.

4 is a flowchart illustrating a method of manufacturing a silicon thin plate using a continuous casting method according to an embodiment of the present invention.

Referring to FIG. 4, the illustrated method of manufacturing a silicon thin plate includes a lower transfer substrate preheating step (S410), a silicon raw material loading step (S420), a silicon melt forming step (S430), a gate opening step (S440), and a silicon melt storage step. (S450), silicon melt discharging step (S460) and silicon thin film forming step (S470).

In the lower transfer substrate preheating step (S410), the lower transfer substrate which forms the discharge part on the lower side of the molten silicon storage unit is preheated.

The lower transfer substrate is preferably made of a material having good wettability, high corrosion resistance, and a higher melting point than silicon. In addition, in order to easily separate the silicon thin plate after cooling, the lower transfer substrate is preferably made of a material having a different coefficient of thermal expansion from silicon. The lower transfer substrate may be made of SiC, Si ₃ N ₄ , graphite, graphite, high density carbon, Al ₂ O ₃ , molybdenum (Mo), and the like.

The lower transfer substrate preheating step (S410) may be such that the preheating of the lower transfer substrate is completed before the gate opening step (S440) or the molten silicon storage step (S450). It is not necessary to preheat the transfer substrate.

In the silicon raw material charging step (S420), the silicon raw material is charged into the silicon melting unit from the silicon raw material input unit.

In the forming of the molten silicon (S430), the silicon raw material charged in the silicon melting part is melted to form the molten silicon. The melting of the silicon raw material may be an induction melting method, and for this purpose, the silicon melting part stores the silicon raw material and has a tapping part formed at the bottom thereof, an induction coil surrounding the crucible outer wall, and opening and closing the tapping part. It may include a gate.

In addition, the crucible may be a graphite crucible, where the graphite crucible may use a graphite crucible having a cylindrical structure in which a plurality of longitudinal slits are formed through the outer wall and the inner wall, as shown in FIG. 2. have. In addition, as shown in FIG. 3, the graphite crucible may be one in which a plurality of longitudinal slits are further formed in the center direction from the edge of the bottom surface of the crucible.

In the gate opening step S440, the gate under the silicon melting part is opened to tap the formed silicon melt.

In the molten silicon storage step (S450), the molten silicon melted from the molten silicon part by the gate opening is stored.

In the silicon melt discharging step S460, the lower transfer substrate is driven in a horizontal direction to discharge the silicon melt through the discharge unit.

In the silicon thin plate forming step (S470), the silicon melt conveyed by the lower transfer substrate is cooled to form a silicon thin plate.

In the cooling of the silicon melt, an inert gas blowing method may be used, and the inert gas may typically present argon gas, and in addition, helium gas, nitrogen gas, or the like may be used.

As described above, the surface temperature of the silicon melt in the silicon melt storage unit is 1300 ~ 1400 ℃, preheating the lower transfer substrate to 800 ~ 1400 ℃, the lower transfer substrate at a speed of 300 ~ 1400 cm / min It is desirable to control the process variables to drive.

5 and 6 are photographs showing the surface and the bottom surface of the silicon thin film manufactured by the method shown in FIG. 4, having a size of 50 × 50 mm and a thickness of about 360 μm. FIG. 7 is a photograph showing the surface after polishing the surface of the silicon thin plate shown in FIG. 5, and the thickness is about 300 μm.

When inert gas blowing is not applied, the surface of the silicon thin plate has an uneven surface. The liquid phase density of silicon is approximately 2.57 g / cm ³ and the solid phase density of silicon is approximately 2.33 g / cm ³ . As a result of the lower solid phase density of the silicon, the volume expands when the silicon cools from the liquid phase to the solid phase, and the surface becomes uneven if not evenly expanded. Therefore, the surface quality of the silicon thin film produced is not good.

However, as shown in FIG. 5, when the inert gas blowing, in particular the argon gas blowing, is performed, it can be seen that the silicon sheet produced has excellent surface quality. However, in the case of FIG. 5, the surface roughness of the manufactured silicon thin plate is large, so that the surface of the silicon thin plate may be polished as shown in FIG. 7 to be used as a solar cell substrate.

The silicon substrate for solar cells uses what has a thickness of 200-400 micrometers normally. Therefore, when the thickness of the silicon thin plate manufactured by the method shown in Figure 4 is also adjusted to 200 ~ 400㎛, it can be easily applied to the solar cell substrate.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. I will understand.

Therefore, the true technical protection scope of the present invention will be defined by the claims below.

110: silicon raw material inlet 120: silicon melter
121: crucible 122: induction coil
123: tapping section 124: gate
130: molten silicon storage unit 132: discharge part
140: lower transfer substrate 142: preheating unit
150: silicon thin film forming portion 210: outer wall
220: inner wall 230,310: slit
240: bottom surface

Claims (17)

A silicon raw material input portion to which a silicon raw material is supplied;
A silicon melting part for melting the supplied silicon raw material by induction melting to form a silicon melt;
A silicon molten metal storage unit configured to receive and store the molten silicon, and then discharge the molten silicon into a melt having a predetermined thickness;
A lower transfer substrate disposed under the silicon molten metal storage unit and transferring the discharged silicon melt; And
It includes; silicon thin film forming unit for forming a thin plate by cooling the transferred silicon melt;
The silicon melting part stores the silicon raw material, and includes a crucible having a tapping part formed at a lower part thereof, an induction coil surrounding the crucible outer wall, and a gate opening and closing the tapping part,
The surface temperature of the silicon melt in the silicon melt storage unit is 1300 ~ 1400 ℃, the temperature of the lower transfer substrate is 800 ~ 1400 ℃, the moving speed of the lower transfer substrate is characterized in that 300 ~ 1400 cm / min Silicon sheet manufacturing apparatus using a continuous casting method.
delete delete The method of claim 1,
The crucible is
An apparatus for producing a silicon thin plate using a continuous casting method, characterized in that the graphite crucible has a cylindrical structure in which a plurality of longitudinal slits penetrate the outer wall and the inner wall.
The method of claim 4, wherein
The silicon melt formed in the silicon melt is
Apparatus for producing a silicon thin plate using the continuous casting method, characterized in that the induction melting without contacting the inner wall of the graphite crucible by the electromagnetic force acting in the center of the graphite crucible.
The method of claim 1,
Apparatus for producing a thin silicon plate using the continuous casting method, characterized in that the lower transfer substrate defines a lower surface of the molten silicon storage portion.
The method of claim 1,
The molten silicon storage unit
The discharge part for discharging the molten silicon is formed on one side of the lower side,
The lower surface of the discharge portion is a silicon thin film manufacturing apparatus using the continuous casting method, characterized in that defined by the lower transfer substrate.
The method of claim 7, wherein
The thickness of the discharge portion is a silicon thin film manufacturing apparatus using a continuous casting method, characterized in that the 0.2 to 2 mm.
The method of claim 1,
The lower transfer substrate is a silicon thin plate manufacturing apparatus using a continuous casting method, characterized in that formed of a material different from the silicon and the thermal expansion coefficient.
10. The method of claim 9,
The lower transfer substrate is
SiC, Si ₃ N ₄ , graphite (Graphite), high-density carbon, Al ₂ O ₃ and molybdenum (Mo) formed of a material selected from the silicon thin plate manufacturing apparatus using a continuous casting method.
The method of claim 1,
The silicon sheet forming portion
An apparatus for producing a thin silicon sheet using a continuous casting method, characterized in that the silicon melt is cooled by an inert gas blowing.
In the method of manufacturing a silicon thin plate using the apparatus of claim 1,
(a) preheating the lower transfer substrate forming a discharge unit on one lower side of the molten silicon storage unit;
(b) charging the silicon raw material into the silicon melt;
(c) melting a silicon raw material charged in the silicon melt to form a silicon melt;
(d) tapping the molten silicon by opening a gate under the silicon melt;
(e) storing the melted silicon melt in the silicon melt storage unit;
(f) driving the lower transfer substrate to discharge the silicon melt; And
(g) cooling the silicon melt conveyed by the lower transfer substrate to form a thin plate; a silicon thin film manufacturing method using a continuous casting method comprising a.
The method of claim 12,
In step (a), the lower transfer substrate is preheated to 800 ~ 1400 ℃,
In step (e), the internal temperature of the silicon molten metal storage unit is adjusted such that the surface temperature of the silicon molten metal becomes 1300 to 1400 ° C.,
Method for manufacturing a silicon thin plate using the continuous casting method characterized in that for driving the lower transfer substrate at a speed of 300 ~ 1400 cm / min in the step (f).
The method of claim 12,
The step (c)
A method of manufacturing a silicon thin plate using a continuous casting method, characterized in that the silicon raw material is melted by an induction melting method.
The method of claim 12,
The lower transfer substrate is
A method of manufacturing a thin silicon sheet using a continuous casting method, characterized in that the silicon and the thermal expansion coefficient is different.
The method of claim 12,
The step (g) is a silicon thin film manufacturing method using a continuous casting method characterized in that for cooling the molten silicon conveyed in an inert gas blowing method.
Made by the method according to any one of claims 12 to 16,
Silicon substrate for solar cells having a thickness of 200 ~ 400㎛.

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